Hi,
Please replace below code
var count = parseInt($(button).closest('[id*=dtListOtherItems]').find('[id*=txtOrderQty]').val()) || 0;
$(button).closest('[id*=dtListOtherItems]').find('[id*=txtOrderQty]').val(count + 1);
with
var count = parseInt($(button).closest('td').find('[id*=txtOrderQty]').val()) || 0;
$(button).closest('td').find('[id*=txtOrderQty]').val(count + 1);
I hope this will help you out.